public class BinaryTree {
    static class TreeNode{
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }
    //手动创建二叉树节点
    public TreeNode creatTree(){
        TreeNode A=new TreeNode('A');
        TreeNode B=new TreeNode('B');
        TreeNode C=new TreeNode('C');
        TreeNode D=new TreeNode('D');
        TreeNode E=new TreeNode('E');
        TreeNode F=new TreeNode('F');
        TreeNode G=new TreeNode('G');
        TreeNode H=new TreeNode('H');
        A.left=B;
        A.right=C;
        B.left=D;
        B.right=E;
        C.left=F;
        C.right=G;
        E.right=H;
        return A;
    }

    //前序打印二叉树
    void preOrder(TreeNode root){
        if(root==null){
            return;
        }
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    //中序打印二叉树
    void inOrder(TreeNode root) {
        if(root==null){
            return;
        }
        inOrder(root.left);
        System.out.print(root.val+" ");
        inOrder(root.right);
    }

    //后序打印二叉树
    void postOrder(TreeNode root){
        if(root==null){
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val+" ");
    }

    //获取树中节点的个数
    public int size(TreeNode root){
        if(root==null){
            return 0;
        }
        return size(root.left)+size(root.right)+1;
    }

    //获取叶子节点个数
    public int getLeafNode(TreeNode root){
        int leafSize=0;
        if(root==null){
            return 0;
        }
        if(root.left==null&&root.right==null){
            return 1;
        }
        return getLeafNode(root.left)+getLeafNode(root.right);
    }

    //求第k层节点的个数
    public int getLevelNodeCount(TreeNode root,int k){
        if(root==null){
            return 0;
        }
        if(k==1){
            return 1;
        }
        return getLevelNodeCount(root.left,k-1)+getLevelNodeCount(root.right,k-1);
    }

    //获取二叉树的高度
    public int getHeight(TreeNode root){
        if(root==null){
            return 0;
        }
        int leftHeight=getHeight(root.left);
        int rightHeight=getHeight(root.right);
        return Math.max(leftHeight,rightHeight)+1;
    }

    //检测value值是否存在
    public TreeNode findVal(TreeNode root,char val){
        if(root==null){
            return null;
        }
        if(root.val==val){
            return root;
        }
        TreeNode leftT=findVal(root.left,val);
        if(leftT!=null){
            return leftT;
        }
        TreeNode rightT=findVal(root.right,val);
        if(rightT!=null){
            return rightT;
        }
        return null;
    }
}
